Depending on what applications you've got installed on your BlackBerry smartphone, you may have noticed some apps waiting to be installed from the "uninstalled" tab in App World when you load that up.

Personally it's a nice touch if some developers do offer that, it really just makes it easier to have one consolidated list of applications. Now this is heavily dependent on the developer. As well as slightly on RIM.

Apparently if you use different signing keys you can't upload an update for that app.

Scenario: App is accepted into App World, I classified it as a PlayBook app. Its up for grabs as a free download in app world and everything is fine and dandy.

Lose your signing keys, reinstall windows, etc. What ever the case may be now you need new signing keys. You get those and you're back in business to creating apps. At this point you cannot upload an update to that app.

So lets say if I wanted to update my app to include BlackBerry 10 support. Can't upload a file under that same listing. Why? It's because I didn't use the same signing keys that I did when I initially created that app.

It gets worse for paid apps, if I designated this app to be paid, and free for those who downloaded the smartphone version for a price, I can't do that because I have to make it under a separate listing. Now I know RIM probably does this for security reasons, but it can get quite a bit annoying at times.

Depending on what applications you've got installed on your BlackBerry smartphone, you may have noticed some apps waiting to be installed from the "uninstalled" tab in App World when you load that up.

Personally it's a nice touch if some developers do offer that, it really just makes it easier to have one consolidated list of applications. Now this is heavily dependent on the developer. As well as slightly on RIM.

Apparently if you use different signing keys you can't upload an update for that app.

Scenario: App is accepted into App World, I classified it as a PlayBook app. Its up for grabs as a free download in app world and everything is fine and dandy.

Lose your signing keys, reinstall windows, etc. What ever the case may be now you need new signing keys. You get those and you're back in business to creating apps. At this point you cannot upload an update to that app.

So lets say if I wanted to update my app to include BlackBerry 10 support. Can't upload a file under that same listing. Why? It's because I didn't use the same signing keys that I did when I initially created that app.

It gets worse for paid apps, if I designated this app to be paid, and free for those who downloaded the smartphone version for a price, I can't do that because I have to make it under a separate listing. Now I know RIM probably does this for security reasons, but it can get quite a bit annoying at times.

Been there. It's really, really, really stupid.

But there are ways to back up the whole lot of stuff that allows you to sign your apps. I'll post the procedure when I find it (lost it along with my previous set of keys ><).

EDIT: Correct me if I am wrong, but I believe that the barsigner.csk, barsigner.db and <CERTNAME>.p12 files located in C:\Users\<USER>\AppData\Local\Research In Motion, along with the signing keys you have, are the files you need to back up in order to avoid such issue.

And to the OP: My app will be available for everything BB for free, provided it's OS5+. I hope all other devs do the same.

Actually many iOS apps are universal apps that you buy once and can use on any device - iPad, iPhone, or iPod Touch. Some apps are iPad only, and some developers do release separate iPad and iPhone versions but that is becoming more uncommon.

As far as I am concerned, the decision whether to charge again depends on the amount of work required to support the new platform, and whether it makes sense for the user.

The app on a phone is likely to be different to the app on a tablet. Anything but the most trivial of apps should be optimized for the use case. On a phone, the steps required to complete the most frequent tasks must be optimized for on-the-go, one-handed usage. On a tablet, which is normally used when you're in less of a hurry, stationary and seated, an app can have more advanced features in a different UI.

Also, when BB10 phones are launched we probably won't have Cascades and various other features on PlayBook. It is not yet known whether the PlayBook will eventually have feature parity with the phones.

As App World has only one description, one set of screenshots and one list of reviews/ratings, it may be difficult or undesirable to consolidate both the phone and tablet versions into one app entry.